Exercises [Pages 61 - 62]
Balbharati solutions for Chemistry 12th Standard HSC for Maharashtra State Board Chapter 3 Ionic Equilibria Exercises [Pages 61 - 62]
Exercises | Q 1.1 | Page 61
Choose the most correct answer:
The pH of 10-8 M of HCl is ____________
8
7
less than 7
greater than 7
SOLUTION
The pH of 10-8 M of HCl is less than 7.
Concept: The pH Scale
Exercises | Q 1.2 | Page 61
Choose the most correct answer:
Which of the following solution will have a pH value equal to 1.0?
50 mL of 0.1M HCl + 50mL of 0.1M NaOH
60 mL of 0.1M HCl + 40mL of 0.1M NaOH
20 mL of 0.1M HCl + 80mL of 0.1M NaOH
75 mL of 0.2M HCl + 25mL of 0.2M NaOH
SOLUTION
75 mL of 0.2M HCl + 25mL of 0.2M NaOH
Concept: The pH Scale
Exercises | Q 1.3 | Page 61
Choose the most correct answer:
Which of the following is a buffer solution?
CH3COONa + NaCl in water
CH3COOH + HCl in water
CH3COOH + CH3COONa in water
HCl + NH4Cl in water
SOLUTION
CH3COOH + CH3COONa in water
Concept: Buffer Solutions
Exercises | Q 1.4 | Page 61
Choose the most correct answer :
The solubility product of a sparingly soluble salt AX is 5.2 × 10-13. Its solubility in mol dm-3 is ______.
7.2 × 10-7
1.35 × 10-4
7.2 × 10-8
13.5 × 10-8
SOLUTION
The solubility product of a sparingly soluble salt AX is 5.2 × 10-13. Its solubility in mol dm-3 is 7.2 × 10-7.
Concept: Solubility Product - Solubility product
Exercises | Q 1.5 | Page 61
Choose the most correct answer :
Blood in the human body is highly buffered at a pH of ________.
7.4
7.0
6.9
8.1
SOLUTION
Blood in the human body is highly buffered at a pH of 7.4.
Concept: The pH Scale
Exercises | Q 1.6 | Page 61
Choose the most correct answer :
The conjugate base of [Zn(H2O)4]2⊕ is __________.
[Zn(H2O)4]2-NH3
[Zn(H2O)3]2-
[Zn(H2O)3OH]⊕
[Zn(H2O)H]3⊕
SOLUTION
The conjugate base of [Zn(H2O)4]2⊕ is [Zn(H2O)3OH]⊕.
Concept: Acids and Bases
Exercises | Q 1.7 | Page 61
Choose the most correct answer :
For pH > 7 the hydronium ion concentration would be _________.
10-7M
< 10-7M
> 10-7M
≥ 10-7M
SOLUTION
For pH > 7 the hydronium ion concentration would be < 10-7M .
Concept: The pH Scale
Exercises | Q 2.01 | Page 61
Answer the following in one sentence :
Why cations are Lewis acids?
SOLUTION
Cations are electron-deficient species and can accept an electron pair. Hence, cations are Lewis acids.
Exercises | Q 2.02 | Page 61
Answer the following in one sentence :
Why is KCl solution neutral to litmus?
SOLUTION
KCl, being salt of a strong acid (HCl) and a strong base (KOH), does not undergo hydrolysis. Hence, the KCl solution is neutral to litmus.
Exercises | Q 2.03 | Page 61
Answer the following in one sentence :
How are basic buffer solutions prepared?
SOLUTION
Basic buffer solutions are prepared by mixing aqueous solutions of a weak base and its salt with strong acid.
Exercises | Q 2.04 | Page 61
Answer the following in one sentence :
The dissociation constant of acetic acid is 1.8 × 10-5. Calculate percent dissociation of acetic acid in 0.01 M solution.
SOLUTION
Exercises | Q 2.05 | Page 61
Answer the following in one sentence :
Write one property of a buffer solution.
SOLUTION
Properties of buffer solution:
i. When a small amount of strong acid (or strong base) is added to a buffer solution, there is no significant change in the value of pH.
ii. The pH of a buffer solution is independent of the volume of the solution. Hence, the dilution of a buffer solution will not change its pH.
iii. The pH of a buffer solution does not change even if it is kept for a long time.
Exercises | Q 2.06 | Page 61
Answer the following in one sentence :
The pH of a solution is 6.06. Calculate its H⊕ ion concentration.
SOLUTION
Exercises | Q 2.07 | Page 61
Answer the following in one sentence :
Calculate the pH of 0.01 M sulphuric acid.
SOLUTION
Exercises | Q 2.08 | Page 61
Answer the following in one sentence :
The dissociation of H2S is suppressed in the presence of HCl. Name the phenomenon.
SOLUTION
The phenomenon due to which dissociation of H2S is suppressed in the presence of HCl is known as the common ion effect.
Exercises | Q 2.09 | Page 61
Answer the following in one sentence :
Why is it necessary to add H2SO4 while preparing the solution of CuSO4?
SOLUTION
Exercises | Q 2.1 | Page 61
Answer the following in one sentence :
Classify the following buffers into different types :
CH3COOH + CH3COONa
Acidic buffer
Basic buffer
SOLUTION
CH3COOH + CH3COONa - Acidic buffer
Exercises | Q 2.1 | Page 61
Answer the following in one sentence :
Classify the following buffers into different types :
NH4OH + NH4Cl
Acidic buffer
Basic buffer
SOLUTION
NH4OH + NH4Cl - Basic buffer
Exercises | Q 2.1 | Page 61
Answer the following in one sentence :
Classify the following buffers into different types :
Sodium benzoate + benzoic acid
Acidic buffer
Basic buffer
SOLUTION
Sodium benzoate + benzoic acid - Acidic buffer
Exercises | Q 2.1 | Page 61
Answer the following in one sentence :
Classify the following buffers into different types :
Cu(OH)2 + CuCl2
Acidic buffer
Basic buffer
SOLUTION
Cu(OH)2 + CuCl2 - Basic buffer
Exercises | Q 3.01 | Page 62
Answer the following in brief :
What are acids and bases according to Arrhenius theory?
SOLUTION
Exercises | Q 3.02 | Page 62
Answer the following in brief :
What is meant by conjugate acid-base pair?
SOLUTION
i. The base produced by accepting the proton from acid is the conjugate base of that acid.
ii. Similarly, the acid produced when a base accepts a proton is called the conjugate acid of that base.
iii. A pair of an acid and a base differing by a proton is said to be a conjugate acid-base pair.
Diagram UPLOAD FROM TEXTBOOK
Exercises | Q 3.03 | Page 62
Answer the following in brief :
Exercises | Q 3.04 | Page 62
Answer the following in brief :
Write a reaction in which water acts as a base.
SOLUTION
Insert Picture Direct.
Exercises | Q 3.05 | Page 62
Answer the following in brief :
Ammonia serves as a Lewis base whereas AlCl3 is Lewis acid. Explain.
SOLUTION
i. According to Lewis's theory, an acid is a substance that can accept a share in an electron pair. In the AlCl3 molecule, the octet of Al is incomplete. Therefore, it can accept an electron pair to complete its octet. Hence, AlCl3 acts as a Lewis acid.
ii. According to Lewis's theory, a base is a substance that can donate an electron pair. In the ammonia (NH3) molecule, the nitrogen atom has one lone pair of electrons to donate. Hence, NH3 acts as a Lewis base.
Exercises | Q 3.06 | Page 62
Answer the following in brief :
Acetic acid is 5% ionised in its decimolar solution. Calculate the dissociation constant of acid.
SOLUTION
Exercises | Q 3.07 | Page 62
Answer the following in brief :
Derive the relation pH + pOH = 14.
SOLUTION
Exercises | Q 3.08 | Page 62
Answer the following in brief :
The aqueous solution of sodium carbonate is alkaline whereas the aqueous solution of ammonium chloride is acidic. Explain.
SOLUTION
Exercises | Q 3.09 | Page 62
Answer the following in brief :
The pH of a weak monobasic acid is 3.2 in its 0.02 M solution. Calculate its dissociation constant.
SOLUTION
Exercises | Q 3.1 | Page 62
Answer the following in brief :
In NaOH solution [OH-] is 2.87 × 10-4. Calculate the pH of the solution.
SOLUTION
Exercises | Q 4.01 | Page 62
Answer the following :
Define the degree of dissociation
SOLUTION
Exercises | Q 4.01 | Page 62
Answer the following :
Derive Ostwald's dilution law for the CH3COOH.
SOLUTION
Exercises | Q 4.02 | Page 62
SOLUTION
Exercises | Q 4.02 | Page 62
SOLUTION
Exercises | Q 4.02 | Page 62
Answer the following in brief :
Derive the relation pH + pOH = 14.
SOLUTION
Exercises | Q 4.03 | Page 62
Answer the following :
What is meant by hydrolysis?
SOLUTION
Exercises | Q 4.03 | Page 62
Answer the following :
A solution of CH3COONH4 is neutral. why?
SOLUTION
Exercises | Q 4.04 | Page 62
Answer the following :
The dissociation of HCN is suppressed by the addition of HCl. Explain.
SOLUTION
Exercises | Q 4.05 | Page 62
Answer the following :
Derive the relationship between the degree of dissociation and dissociation constant in weak electrolytes.
SOLUTION
Exercises | Q 4.06 | Page 62
Answer the following :
Sulfides of the cation of group II are precipitated in acidic solution (H2S + HCl) whereas sulfides of cations of group IIIB are precipitated in the ammoniacal solution of H2S. Comment on the relative values of the solubility product of sulfides of these.
SOLUTION
Exercises | Q 4.07 | Page 62
Answer the following :
The solubility of a sparingly soluble salt gets affected in the presence of a soluble salt having one common ion. Explain.
SOLUTION
Exercises | Q 4.08 | Page 62
Answer the following :
The pH of rainwater collected in a certain region of Maharashtra on a particular day was 5.1. Calculate the H+ ion concentration of the rainwater and its percent dissociation.
SOLUTION
Exercises | Q 4.09 | Page 62
Answer the following :
Explain the relation between ionic product and solubility product to predict whether a precipitate will form when two solutions are mixed?
SOLUTION
